1. Field of Invention
The present invention relates to radioactive well logging.
2. Description of Prior Art
U.S. Pat. Nos. 4,051,368; 4,169,979 and 4,486,658, all assigned to the assignee of the present application, involve determining horizontal brine flow speed of brines in a formation past a well borehole. In these patents formation brine is bombarded with neutrons from a neutron source in a sonde lowered by wire line into a well borehole. The neutrons are slowed to thermal energy level. When the brine is saline, the nuclear reaction .sup.23 Na (n, .gamma.) .sup.24 Na occurs. One or more gamma ray detectors in the sonde measures gamma radiation from this nuclear reaction. The gamma radiation measurements are then processed to determine horizontal brine flow.
U.S. Pat. No. 4,051,368 related to determining the location and horizontal flow rate of earth formation brines past a well borehole. U.S. Pat. No. 4,169,979 related to measuring the azimuth and speed of horizontal brine flow by a well borehole. U.S. Pat. No. 4,486,658 related to displacing borehole brine away from the sonde, and thus the detectors, to remove any contribution of borehole salt water to the gamma ray measurements.